Dear Editor and Reviewers： Thank you very much for your comments on our manuscript [acp-2018-255]. We acknowledge the suggestions of two anonymous reviewers and are grateful to your efficient serving. We have updated the manuscript based on these valuable comments and suggestions, and the point-by-point responses are listed below. Referee #1 General comments: The authors focused on air quality along the Yangtze River based on a shipboard observation performed in winter of 2015. Over the past few decades, China’s rapid development leads to huge cargo transports in the Yangtze River channel. However, there is lack of data for ship emission along the Yangtze River channel, especially in the inland area. From this viewpoint, this manuscript supplied value data and made some contributions to portray a picture of air pollution along the Yangtze River. However, the manuscript suffered from poor English written. There are a lot of wrong spelling, tedious sentence, vague expression. Generally, the manuscript is difficult to read and should be improved greatly before publication. Response: Thank for reviewer’s valuable comments. In the new version, we have updated the manuscript on the basis of the comments. Especially, we have improved the English presentation greatly, including grammar and typing mistake throughout the manuscript. Specific comments: 1), Line 4 what mean “onboard and coastal areas”. Response: It means “people living along the Yangtze”. This sentence has been changed to “Air quality over the Yangtze River is interesting as it may have significant influences on the aquatic ecosystem, the health of everyone living along the Yangtze River, and regional climate change.” 2), Line 7 After the sentence of “Based on the filter samples,……”, the PM2.5 concentration during the cruise campaign should be shown. Response: We have added the PM2.5 in Abstract. “The total average concentration of PM2.5 were 119.29 -3 2- ± g m , and the dominate ionic composition in PM2.5 was were SO 4 with the average 1 -3 - -3 + concentration of 15.21 ± 6.69 g m , followed by one of NO3 (13.76 ± 4.99g m ), NH4 (9.38 ± 4.35g m-3), Ca2+(2.23 ± 1.24g m-3) in this cruise.” 3), Line 44-55 Authors cited a few of literatures focused on air quality on the region of Yangtze River Delta. In my opinion, authors should expand these literatures to the MLYR region, of which is overlapped well with the present region. Furthermore, the author should show specific regions shown in cited literatures. Response: This was changed. To best our knowledge, numerous studies have been conducted in megacities in the MLYP region, especially Nanjing and Shanghai. Of course, there are also many papers which were related to air quality in other cities or rural in YRD region. However, we still thought long- time observation and sampling on air quality were only focused in Nanjing and Shanghai. 4), Line How about the T/B values for EP3 and EP5? Response: We have re-calculated our data, and new results have been changed in the new manuscript in Table 2. Air mass with T/B ratio ≥ 2 were identified from fresh emissions. As shown in Figure S2, the peak value of T/B ratio clearly performed in EP-3 and EP-5, suggesting fresh emission dominant. Figure S2. Time series of meteorological parameters during YRC (T and RH). (b) Time series of ratio of Toluene to Benzene. 5), Line 214 there are two “with”. This sentence should be written. Response: This sentence has been changed to “The local air during EP-4 was in low pressure system with low wind speeds that didn’t favor the diffusion of the local pollution”. 6), Line 292-293 “……, accounting for 37.43% and 40.15% in PM2.5 and PM1.0?”, gained in the present study? 2 Response: Yes, these data all acquired from this cruse. This sentence has been changed to “……, accounting for 37.43% and 40.15% in PM2.5 and PM1.0 during YRC, respectively” 5, Line 462 “……and the YDR, Jiangsu, east of Anhui, and the Mongolian plateau were identified as the major source regions, and pathways.” This sentence should be rewritten. Response: this sentence has changed to “Fine particles Ni (Figure 6i) had almost same spatial distribution with Cr, that Shanghai, Jiangsu, and East of Anhui, and the Mongolian plateau were identified as the major potential source regions or pathways, owing to ship emissions, nonferrous metal mining, and smelting industries. The Mongolian plateau also was a source region, indicating that nature dust may be possible source for Cr and Ni.” Technique corrections: (1) Line 3 “River” is changed to be “river”. (2) Line 11 “the secondary inorganic formation” should be changed to “the secondary inorganic aerosol formation”. (3) Line 19 “This result……”should be changed to “The results”. (4) Line 35 “their effects” should be changed to “their negative effects”. (5) Line 40 “……and possible sources in this region have been generally characterized” should be changed to “……and source identification in this region have been generally studied”. (6) Line 63 “The MLYR” should be changed to “The MLYR region”, and “effecting its air quality” should be deleted. (7) Line 68 “particle matter” should be abbreviated to be “PM”. (8) Line 77 “noted” should be changed to “pointed out”. (9) Line 79 “Shanghai port” should be changed to “The Shanghai port”. (10) Line 83 “the air quality” should be changed to “air quality”. (11) Line 93 “to the best of our knowledge, it is the first systematic observation to characterize the air pollution along the China’s largest and longest river” should be changed to “to the best of our knowledge, it is the first systematic observation on air pollution along the Yangtze River”. (12) Line 97 “A mobile haze monitoring platform” should be changed to “A mobile monitoring platform”. (13) Line 204-205 A sentence should be added here to explain the T/B value for weather 3 identification, although it has been explained in the Experimental section. (14) Line 206 “supplements” should be changed to “supporting information”. (15) Line 217 “in the sixth episode” should be changed to “For the sixth episode”. (16) Line 233 “Their detail information” should be changed to “The detailed information”. (17) Line 245 “……, mainly owing to local emissions, photochemical processes and meteorology conditions (Xu et al., 2011)” should be deleted. (18) Line 247 “cities” was changed to “the cities”. (19) Line 252 “was substantially enhanced” should be changed to “increased”. (20) Line 261 “the mean levels” should be changed to “the mean level”. (21) Line263 “revealed” should be changed to “was characterized by”. (22) Line 264 “edge” should be changed to “banks”. (23) Line 266 “by” should be changed to “identified by”. (24) Line 268 “regionally” should be changed to “apparently”. (25) Line 430 “the similar source region distributions” should be changed to “the similar region distributions”. (26) Line 542 “It is noted that” should be changed to “It was noted that”. (27) Line 564 “the YRD regions” should be changed to “the YRD region”. (28) Line 567 “Ship engine emission” should be changed to “Ship emission”. Response: We have followed these valuable suggestions and made the corrections accordingly. Referee #2 General comments: General comment: This manuscript aims to provide a good picture of air pollution in the Mid- Lower Reaches Yangtze River (MLYR) based on a 15-day cruise campaign in winter of 2015. With chemical speciation data from filter samples, sources impacting the MLYR region are discussed including coal combustion, ship emission, biomass burning etc. Although these are important data, there are still some limitations of this work. One is the number of samples is limited, and the other is that in the data analysis section, it is pretty descriptive. Instead, there should be more in-depth discussion and it should be more logic and structured. With the current information provided in 4 the manuscript, it is hard to draw firm conclusions. Therefore, I suggest the authors to revise the manuscript with in-depth data analysis and provide clear and new conclusions. Response: We thank the reviewer for their helpful comments and suggestions, which are helpful for the improvement of the manuscript. We also have in-depth re-analyzed our data and revised the manuscript carefully according to the reviewer’s comments. Specific comments: 1). Why is levoglucosan from satellite data instead of from filter samples? What about the spatial resolution of satellite data? The authors indicate that biomass burning may make a big contribution to rural area. It will be more interesting to know the quantitative contribution from biomass burning. Response: Thank for reviewer’s valuable comments. The mass concentration of levoglucosan were analyzed from filter samples (PM2.5) by IC methods. We just acquired the value aerosol optical depth (AOD), and SO2, CO, NO2 column concentration from Satellite data. We have added spatial resolution of satellite datasets in section 2.4. “Based on spatial interpolation methods, all of data from satellite datasets were interpolated and averaged into grid cells with a 0.25° × 0.25° resolution”. Thank you for interesting in biomass burning event in rural region along over MLYP region. As you suggested, we also try to quantify the contribution of biomass burning to particulate matter. In general, both K+ and levoglucosan (lev) could be regarded as tracers for biomass burning. However, significantly 2+ + + correlation between Ca and K suggested that dust could be the major source of K in PM2.5 sampled during YRC. Meanwhile, numerous studies have confirmed that lev mostly originate from biomass burning. Hence, the levoglucosan concentration and ratio of OC to lev (OC/lev) were widely used to estimate the contribution of biomass burning to organic carbon.